Snap action high voltage earthing switch - uses rotating rod with threaded plate to compress main spring and displace ball detent blocks to release spring

摘要

The switch uses the compression between a spring, an spring loaded ball detents to give sharp opening and closure of the earthing switch. The switch operates in a closed chamber filled with sulphur hexafluoride gas under pressure. The high voltage conductor is supported on either side of the sealed enclosure by conical insulators. Fingers protrude from the conductor to receive the earthed moving contact, which has a shoulder against which rests the ball insert of a sprung lever. A threaded rod passes along a threaded passage in the rod which supports the mobile contact, and, when the rod is rotated, an end plate threaded to it advances, compressing the main spring and eventually displacing notched blocks which allow the ball detents to move clear of the mobile contact which is then rapidly closed by the compressed spring.